请讲讲这道题---The extracted content from the image is as follows: **Question 15** **Question Stem:** 15. 如图, 已知直线l₁//l₂, ∠1 = 55°, ∠2 = 100°, 则∠A为( ) (Translation: As shown in the figure, given that lines l₁//l₂, ∠1 = 55°, ∠2 = 100°, then ∠A is ( )) **Options:** A. 45° B. 50° C. 55° D. 60° **Chart/Diagram Description:** * **Type:** Geometric figure illustrating a triangle positioned between two parallel lines. * **Main Elements:** * **Lines:** * Two parallel horizontal lines, labeled `l₁` and `l₂`. Line `l₁` is positioned above line `l₂`. * **Shapes:** * A triangle `ABC` is formed. Point `A` is the top vertex of the triangle, located above line `l₁`. Points `B` and `C` are located on line `l₂`, forming the base `BC` of the triangle. * **Connections/Intersections:** * The side `AB` of the triangle intersects line `l₁`. * The side `AC` of the triangle intersects line `l₁`. * The base `BC` of the triangle lies entirely on line `l₂`. * **Points:** * `A`: The top vertex of the triangle. * `B`: The left endpoint of the base, on `l₂`. * `C`: The right endpoint of the base, on `l₂`. * **Angles:** * `∠1`: An angle marked at the intersection of line `AB` and line `l₁`. Its vertex is on `l₁`. The angle is formed between the segment `AB` and the part of `l₁` to the right of the intersection point. It is depicted as an acute angle. * `∠2`: An angle marked at point `C` on line `l₂`. Its vertex is `C`. The angle is formed between the segment `AC` and the part of line `l₂` to the left of point `C`. It is depicted as an obtuse angle. * `∠A`: The interior angle of triangle `ABC` at vertex `A`. This is the angle whose measure is requested by the question. * **Labels and Annotations:** Lines are labeled `l₁` and `l₂`. Vertices of the triangle are labeled `A`, `B`, `C`. Angles are labeled `1` and `2`.